I. Field
The present invention relates generally to circuits, and more specifically to delay elements and oscillators.
II. Background
A delay element is a circuit that can delay an input signal by a particular amount and provide an output signal that is a delayed version of the input signal. A delay element may be used for various purposes such as a delay line, an oscillator, etc. For example, a number of delay elements may be coupled in a loop to form a ring oscillator. The frequency of oscillation may be dependent on the number of delay elements coupled in the loop and the amount of delay provided by each delay element.
A delay element may be implemented with one or more transistors and one or more capacitors. A delay may be obtained by charging and discharging the capacitor(s) via the transistor(s), which may be controlled by an input signal. Circuit components (e.g., transistors) within the delay element may have characteristics that change with temperature. As a result, the amount of delay provided by the delay element may be dependent on temperature. Temperature-dependent delay may be undesirable. For example, the delay element may be used in an oscillator, and the frequency of oscillation may vary with temperature due to changes in the amount of delay provided by the delay element. It may be desirable for the delay element to provide a delay that varies as little as possible with temperature.